ISBN Verifier

Challenge Overview

Check if a given string is a valid ISBN-10 number.

Visit the isbn-verifier exercise on Exercism to read the full instructions and download the exercise files.

Community Solutions

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The following are the top 3 community solutions by stars:

Solution 1 by @amscotti (⭐ 2) — View on Exercism
Solution 2 by @dbalmain (⭐ 1) — View on Exercism
Solution 3 by @heptalophos (⭐ 0) — View on Exercism

Source: Exercism groovy/isbn-verifier

💡 View Solution

class IsbnVerifier {
    static boolean isValid(String isbn) {
        if (!isbn.matches(~/^\d-?\d{3}-?\d{5}-?[\dX]$/)) {
            return false
        }

        isbn.findAll { (it as char).isLetterOrDigit() }.withIndex().collect { c, i ->
            c == 'X' ? 10 : (c as int) * (10 - i)
        }.sum() % 11 == 0
    }